Code P0138 high voltage code, Bank 1 sensor 2? - JeepForum.com

Reply
 
LinkBack Thread Tools
post #1 of 21 Old 05-03-2009, 09:05 PM Thread Starter
crmaverick89
Registered User
2015 JK Wrangler 
 
Join Date: May 2008
Location: Boston
Posts: 100
Code P0138 high voltage code, Bank 1 sensor 2?

My check engine light has been on with a P0138 High voltage code, bank 1 sensor 2. I replace the 02 sensor near the manifold (before the cat) as told to with a Bosch, but the light is still one, even after i reset the code it came back on. I checked my ground to the engine block which is good, and my 15A fuses look good to. Any other ideas as to why it getting high voltage, is the rear 02 sensor causing this and need to be re-placed? Anyone else with this problem figure it out?

thanks

crmaverick89 is offline  
Sponsored Links
Advertisement
 
post #2 of 21 Old 05-03-2009, 09:40 PM
sbrunner
Registered User
1996 XJ Cherokee 
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 160
I had that code also. I replaced the rear o2 sensor and it went away.
sbrunner is offline  
post #3 of 21 Old 05-04-2009, 06:03 AM
x99j
Registered User
 
Join Date: Jan 2005
Location: ohio
Posts: 450
you got the wrong sensor. sensor 2 is the one after the cat so you might want to do more research. mike

06 kj 3.7l, 6speed manual, np241 command track

91 yj 2.5l, ax-5, np 231 3 inck lift, 31'' mud rovers

12 kk 3.7L, 42rle, mp1522, d-30, 8.25.
x99j is offline  
post #4 of 21 Old 05-04-2009, 08:27 AM
Ed Rico
Registered User
1997 XJ Cherokee 
 
Join Date: Jun 2007
Location: Terre Haute
Posts: 527
The rear O2 sensor *is* the one after the cat as pointed out by X99J above, so replacing the front won't resolve this code.

The P0138 high voltage code indicates an open in the rear sensor heater circuit. It may be a bad internal heater within the rear O2 sensor, you could check the heater wires (dark green/white and black) for continuity. If the sensor heater checks out OK, you're stuck with checking the rest of the circuit from the PDC to the ground stud next to the dipstick to find the open.

-Ed Rico

Last edited by Ed Rico; 05-04-2009 at 08:37 AM. Reason: Responded too quickly, sorry for any confusion.
Ed Rico is offline  
post #5 of 21 Old 05-04-2009, 10:14 AM Thread Starter
crmaverick89
Registered User
2015 JK Wrangler 
 
Join Date: May 2008
Location: Boston
Posts: 100
By checking the circuit and wires do you mean checking for melted insulation or using a tester? If the wiring checks out all good ill replace the rear 02 sensor

thanks
crmaverick89 is offline  
post #6 of 21 Old 05-04-2009, 01:12 PM
Ed Rico
Registered User
1997 XJ Cherokee 
 
Join Date: Jun 2007
Location: Terre Haute
Posts: 527
What I meant was using a meter to check the circuit for continuity. But to your point, checking for melted insulation would be helpful and could yield some useful clues to finding the problem. Just be careful when checking the sensor itself to probe the 2 heater wires (colors listed above) and NOT the 2 sensor output wires. You don't want to risk damaging the O2 sensor by applying a voltage across the sensor output, and besides it won't help you solve the problem.

-Ed Rico
Ed Rico is offline  
post #7 of 21 Old 05-04-2009, 04:40 PM
Bnugget
Registered User
2000 XJ Cherokee 
 
Join Date: Mar 2009
Location: Colorado
Posts: 24
After CAT sensor

What does the 2nd sensor do? Adjust fuel mixture, or is it for emmissions only? I'm getting the P0138 now, it seems to be a fairly common code.
Thanks in advance,
Bnugget
Bnugget is offline  
post #8 of 21 Old 05-06-2009, 04:52 AM
Ed Rico
Registered User
1997 XJ Cherokee 
 
Join Date: Jun 2007
Location: Terre Haute
Posts: 527
Rear O2 sensor on OBD-II monitors oxygen content of exhaust stream downstream of the cat. This information is used to compare to the upstream (pre-cat) O2 value in order to determine if the cat is functioning normally. The rear sensor has no direct effect on air/fuel mixture, but can have an important indirect effect since the internal resistance heaters for both sensors are wired in parallel. If a problem with the rear sensor heater knocks out the fuse in the PDC, the front sensor heater is disabled as well which can negatively affect driveability.

-Ed Rico
Ed Rico is offline  
post #9 of 21 Old 05-06-2009, 11:31 AM
kadetklapp
Registered User
1997 XJ Cherokee 
 
Join Date: May 2008
Location: Indiana
Posts: 1,357
I've got this code as well. Weird.

**1997 Jeep Cherokee SE**
Former Police Car assigned to 54-26, RIP.
kadetklapp is offline  
post #10 of 21 Old 05-06-2009, 09:29 PM Thread Starter
crmaverick89
Registered User
2015 JK Wrangler 
 
Join Date: May 2008
Location: Boston
Posts: 100
ya I still haven't figured it out, im gonna try replacing the rear 02 sensor i guess
crmaverick89 is offline  
post #11 of 21 Old 07-02-2009, 05:24 PM
bfolla06
Registered User
2003 TJ Wrangler 
 
Join Date: Nov 2008
Location: NY
Posts: 103
are the front and rear sensors the same?
bfolla06 is offline  
post #12 of 21 Old 07-02-2009, 07:17 PM
Jay-P
Registered User
1992 YJ Wrangler 
 
Join Date: Aug 2002
Location: Winnipeg, MB, Canada
Posts: 290
Quote:
Originally Posted by bfolla06 View Post
are the front and rear sensors the same?
Nope, front adjusts air/fuel ratio, rear just senses oxygen in the exhaust. Read Ed Ricos post above.

1992 YJ + 2012 JKUR
Jay-P is offline  
post #13 of 21 Old 07-03-2009, 09:00 AM
Ed Rico
Registered User
1997 XJ Cherokee 
 
Join Date: Jun 2007
Location: Terre Haute
Posts: 527
Front and rear O2 sensors have physically different connectors, otherwise they are the same. That's why the replacement sensors that require splicing your old connector are the same for front or rear applications.

-Ed Rico
Ed Rico is offline  
post #14 of 21 Old 08-23-2009, 05:38 AM
meldredge1
Registered User
 
Join Date: Aug 2009
Location: Cary, NC
Posts: 1
Fuse location?

My downstream O2 sensor wires (behind the cat) fell on the driveshaft wearing through them. I am having the same hot engine misfires/sputtering problem as described in these posts and the same code. After the sputtering began I spliced the wires together but the problem continues. After reading the Upstream and Downstream O2s run on a parallel circuit I thought I would check the fuse. Do you know where it is located? I thought that possibly the Downstream O2 short may have also shorted the other Upstream o2 sensor? What do you think?

Mike
meldredge1 is offline  
post #15 of 21 Old 08-23-2009, 07:27 AM
Ed Rico
Registered User
1997 XJ Cherokee 
 
Join Date: Jun 2007
Location: Terre Haute
Posts: 527
O2 sensor heater circuit fuse is located in the Power Distributon Center under the hood. If you damaged the wiring to the rear sensor, it likely shorted the heater circuit, effectively knocking out the heater to both sensors.

-Ed Rico
Ed Rico is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Code P0138 - What do I need to fix an O2 sensor Dannyboy18 XJ Cherokee Technical Forum 3 03-24-2011 11:37 AM
Check Engine Light - 02 sensor voltage too high bank 1 sensor 2 billbarr100 XJ Cherokee Technical Forum 15 05-19-2010 03:04 PM
Trouble with oxygen sensor code p0138 123mylesl XJ Cherokee Technical Forum 1 09-15-2008 10:37 PM
code 463: Fuel Level Sensor Circuit High Input??? nickwc XJ Cherokee Technical Forum 1 09-16-2004 06:10 PM
P0138 Oxygen sensor high voltage, bank 1 sensor 2 Back2Basics XJ Cherokee Technical Forum 3 08-03-2004 11:33 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome